Reactor furnace



0a. 31, 1950 I F. s. WHITE 2,528,098-

REACTOR FURNACE Filed Jun. 25. 1947 1 IQ/H: 46 52 1 so lNVENTO R:

FRANK 3. WHITE 5 5 BY Qi-diuu.

59 58 ATTORNEY gaswhich is to react with such solids.

Patented Oct. 31, 1950 REACTOR FURNACE Frank S. White, Westport, Conn,assignor to The Dorr Company, New York, N. Y., a corporation of DelawareApplication June 25, 1947, Serial No. 756,934

Claims. (01. 26321) This invention relates to reactor furnaces whereinfinely divided solids are maintained, during heat-treatment thereof, ina mobilized or fluidized suspension in a stream of uprising A reactor ofthis typeis shown and described in the patent application of White S er.No. 740,151, filed April 8, 1947. In essence, it shows a reactor furnacehaving one or more fluidized bedsof solids supported by a horizontalgrid or perforatedpartition up through which is blown the stream of gasthat fluidizes the solids of the bed. By fluidizing is meant that eachsolid is in suspension, more or less as solids are suspended in a watersuspension. The solids are all in turbulent motion, and they act like afluid, even to the extent of presenting a fluid-level at the top of thefluidized bed.

Gas is passed or blown upwardly through the holes or apertures in thehorizontal partition or diaphragm at a velocity sufficient to fluidizethe solids but insufficient to blow the suspended solids out of thereactor furnace. The holes or apertures, whose length is greater thantheir diameter, tend to clog up at their outlet sections, so it is anobject of this invention to prevent or at least to minimize theformation of such clogging deposits from being formed in the holes orapertures in the diaphragm or partition.

This object is accomplished by providing a retarding or impedingrestriction in the outlet section of each (or at least a major number)of the apertures so that the eifective outlet area of the aperturethrough which the uprising gas must pass to be emitted from the apertureis less or reduced in diameter as compared with the diameter of the mainbore of the "aperture. Such a reducer seems to prevent the formation ofclogging deposits or incrustations. This assures the uniform emission ofgas from the apertures which is necessary for the proper dispersion ofthe rip--v rising gas through the solids of the bed to fluidize them.Such a reducer seems to have odd or unexpected effects, all of which arenot neces sarily understood, but at least it seems to obviate theoperation of centrifugal force upon the gas uprising through theaperture and prevents eddying or turbulence. The gas seems to flowsmoothly through the bore of the aperture with a, minimum of contactsbetween bore and gas because the gas constituents appear to flow in whatmay be termed small elongated filaments rather than in a turbulent ormobilized mass of individual or independent molecules or particles. Thisminimum contact of gas with the bore of the aperture is very importantbecause those particles of gas that do not touch the bore cannot depositany, solids that may be entrained therein. Solids likely to be soentrained are usually calcareous and the phenomenon of deposition ofsuch lime! like solids resembles or is equivalent to what happens if apiece of chalk is thrown against a black-board. There is a small depositof chalk left adhering to the black-board after the piece of chalk fallsor is deflected from the board. This phenomenon seems to be duplicatedin an aperture in a horizonal partition of a fluidizing reactorfurIEcMTQe turbulence, eddying and swirling superimposed on\gguprisingthrough the aperture causes solids (howeversmall) entrained in the gasto be deflected agaifithebore of the aperture and to causefa deposit tobe 'bore of the aperture is substantially closed. Reeducing thecross-sectional area of the emission zone of the aperture to criticalproportions, prevents such turbulence or eddying with the result that inproportion as deflecting contacts between gas and bore are reduced, thedeposition of eloge ging deposits on the bore is substantially elimi-.nated.

To achieve a multi-stage or multi-bed opera.- tion of the aforementionedfluidizing treatment of solids with gases, it is necessary to divide thereactor proper into a series of compartments, by the use of horizontalapertured diaphragms or partitions which define the lower limit of eachsuccessive bed of fluidized solids, and which aper-, tures permit of theupward flow of gas to the bed in such a manner that the solids of thebed are rendered uniformly fluidized.

For moderate temperature furnaces, such as up to 1200 F., a diaphragmcomprising .an apere tured metal plate (sometimes called a constrictionplate) properly supported, is entirely ade-. quate. For highertemperatures, say as high as 1700 F. to 2000 F., it has been foundnecessary to resort to diaphragms fabricated as an arch of refractoryshapes or material. Of necessity these arches are of considerablethickness to withstand the stresses encountered. Apertures or holes orbores extending through such arches for the passage of gas through thearches, have been found to become clogged and closed by a deposit ofvery hard scale made of dust carried by the stream of gas risingthroughthe apertures. It has not been found possible to enlarge theseapertures sufiicient to deter scale formation therein,

for as the gas velocities were decreased, it was no longer possible tomaintain in fluidized condition, the solids of the bed above theapertured diaphragm or arch.

It has been found, however, that if the apertures or bores through thediaphragms are enlarged to a sufficient diameter so that the velocity ofthe gas uprising therethrough is reduced down to the order of feet persecond, and the aperture is capped with a thin edge orifice of heatresistant alloy material such as steel, the proper gas flow conditionscan be obtained for fluidization of the bed of solids thereabove,without the formation of scale or other clogging deposits in the boresin the diaphragms. In other words, this invention proposes to use boresthrough the diaphragms that are larger in diameter than would befeasible per se, and then provide a reducer for each such enlarged bore,whereby the velocity of the gas uprising in the bore (on the L The bestembodiment of the invention now.

known to me has been chosen for the, purpose of illustration but it isto be understood that it is used for illustrativepurposes and not forlimiting/ones lfiuse obviously the invention is carixlble of differentembodiments and structural detai1s,'so long as they fall within theambit of the appended claims.

In the accompanying drawings, Fig. 1 is substantially like Fig. 2 of thepatent application of White, Ser. No. 740,151, filed April 8, 1947,namely a vertical sectional view of a multi-stage or multi-bed reactorfurnace for treating a plurality of beds of fluidized solids with gases.Fig. 2 is an enlarged partial sectional view of a detail of an orificedreducer of this invention in place within a bore of an aperture of anarch or diaphragm of the reactor furnace. Fig. 3 is also an enlargedpartial vertical sectional view through a part of one aperture with anorificed reducer'in place at the top of the aperture showingtheoretically how gas uprises therethrough in filaments with a minimumof turbulence or eddies.

In the drawings, upper section It, adjacent its lower end or bottom, isa gas permeable initial construction diaphragm platform or partition IIpreferably of arch construction, extending substantialy horizontallyacross the section 13 and provided with a multiplicity of perforationsor apertures l8 upwardly through which gas may pass. The plate is madeof heat-resistant metal or refractory material. Supported on andextending upwardly from the plate H is an initial everchanging layer orbed of solids to be treated with gas. These solids are to be fluidizedinto a turbulent mobilized suspension by the gas passed upwardlytherethrough at such velocities that the solids act like a fluid andpresent a fluid level 25, above which is free-boardspace 21. Rising fromthe top region of the initial or upper section I3 is a pipe or conduit28 for conducting dust particles rising from the fluidized layer to acyclone (not shown). Solids separated from entrainment in the gas in thecyclone drop down through pipe 3] to the layer 25 in a region adconstruction plate ll, since the lower end of the pipe 3| is preferablysubmerged in the fluidized layer, as shown.

Solids to be treated in the reactor are supplied thereto from a hopper35 from whence they drop into a conducting or delivery tube or pipe 39that passes through the wall of the reactor and terminates in the layeror bed 25 in a region adjacent the bottom thereof as shown.

The fluid level 25 of the layer or bed 25 is controlled by the elevationof the upper end of a spill-pipe or conduit 4! which pipe extendsdownwardly through the bed 25 and arch partition ll terminatingsubmergedly in an ever-changing layer or bed 22 under treatment in themiddle section ll of the reactor. This bed or layer is fluidized likethe initial bed 25 and has fluid level &3 as well as a free-board spacethereabove. This bed is supported on or from a second or middle gaspermeable constriction diaphragm, platform or plate Ml perforated orapertured as at E8, the same as the initial apertured partition ll.

The fluid level 43 of the second or heat-treatment bed or layer 52 iscontrolled b the elevation of the upper end of a spillpipe or conduit 46which pipe extends downwardly through the fluidized bed jl-andiartition44, terminating submergedly in an ever-changing cooling layer or'bed 59in the bottom section M of the reactor.

This bed is fluidized like the beds 25 and t2 and has a fluid level 5!as well as a free-board space 52 thereabove. This bed or layer 59 issupported on or from a third or bottom constriction diaphragm orpartition 53, perforated or apertured as at (8, the same as inpartitions H and M.

The fluid level 5! of the bottom bed or layer is controlled by adischarge conduit or spillpipe 5 -1 suitably valved as at 55 thatconducts treated solids to a place outside of the reactor. The bottomsection Id of the reactor terminates in a wind-box 58 having an entranceinlet 58 for compressed air or other gas, which the windbox conducts tothe underside of the partition plate 53 so that air therefrom can passupwardly through the apertures therein for the purpose of fluidizing orsuspending or teetering the solids in the bed 5!).

In to the middle or heat-treatment bed 42 may extend suitably valved oilinjection pipes 62 terminating in that bed adjacent the bottom thereof.Spill-pipe M is provided with a closure valve 10, preferablyat its lowerend and in the form of substantially that of a cone or coned plug, whichis controlled to open and close by means of a shaft H extending upwardlythrough the spill-pipe and the top or roof of the reactor to an exteriorcontrol wheel 12. Spill-pipe 46 has its lower end controllably closed bya similar coned valve 73, operated from a downwardly extending shaft 14and an exterior'control wheel similar to 12 for shaft H.

indicates furnace walls of refractory bricks outside of which aresections of insulation I6 and a steel outer casing 11. 18 indicates aremovable manhole to provide access to the interior of the furnace. 19indicates various cleanout openings. indicates various pressure taps,located usually at the top and bottom of each chamber. These tapsindicate the pressure in that zone of the furnace where the taps arelocated and they are suitably connected to a manometer type indicatorboard that can be observed by the furnace operator. Similarly, 8i

jacent the bottom of the layer and close to the 75 d at s a ious tempindicators located generally in the top of a chamber and within the bedor layer of that chamber. These, likewise, are suitably connected to anindicator board that can be observed by the furnace operator. Theapertured partitions H and 44, in this embodiment, are made ofrefractory bricks. In order that the refractory brick constructionplates are strong enough to resist the temperature encountered withoutsagging or warping, it is desirable that the plate be arched as shown,and the bricks tapered from top to bottom.

The operation of the reactor is continuous. Assuming that it hasbeenproperly started-up and the various layers or beds are properlyfluidized by the controlled velocity of gas passing upwardlytherethrough, feed solids are supplied through the feed pipe 39 into thebottom section of the initial or pre-heating layer 25. Solids in layerare preliminarily heated by the hot gases from free-board space uprisingtherethrough from the apertures 58 of the arched partition I]. Dust fromthe bed entrained in gas rising therefrom passes through conduit 28 tothe cyclone wherein the dust particlesv are separated from ""-\t;he gas'and descend through pipe 5! back to the layer 25 for re-treatment, whilegas escapes from thebyclonee Fluidized or teetered solids rising abovethe tTJp of th e spill-pipe or conduit 4! (fluid level 21), spillovepithe top thereof and fall down that pipe to the bottom section ofthe dissociation layer 42 for submerged delivery thereinto.

The main layer 42 where the major reactions are to take place, ismaintained at the desired temperature and in fully fluidized ormobilized condition by gas uprising from free-board space 52therethrough from the apertures It in partition 44. Treated fluidizedsolids rising above the top of the spill-pipe or conduit 46 (fluid level43),

spill over the top thereof and fall down that pipe to the bottom sectionof the cooling layer 56 to the bottom section thereof for submergeddelivery thereinto.

The cooling layer 50 is maintained at cooling temperatures and in fullyfluidized condition by gas rising through apertures l8 in partition 53from the windbox 58. Cooled solids pass from the fluid level 5| of thecooling layer 59 by spilling over and into the upper end of thedischarging spill-pipe or conduit54 to discharge. In this way, eachlayer or bed is not only maintained fluidized but made up ofever-changing solids being treated with gas in such layers.

The main or middle layer 42 is maintained at proper temperature by beingheated controllably thereto. Heating is accomplished by the use of oil,gas or finely divided coal as fuel supplied, for instance, through thepipes or burners 62 leading into that layer.

When starting up, the cone valve 13 at the bottom of spill-pipe 46 isclosed; coned valve H! at the bottom of spill-pipe 4! is closed; andvalve 55 in discharge pipe 54 is also closed. Compressed air or otherrelatively cool gas is admitted to the wind-box 58, which flows upwardlythrough constriction plate 53. The burner or burners 62 are started. Atthis time, the solid material to be treated in the reactor, if notalready fine enough, is crushed to pass a 6 mesh screen, the bulk ofwhich, however, is coarser than 200 mesh, is delivered to the initial orDre-heating layer 25 by means of the feeder elements 3! or 39. The

rising current of hot air will cause, when at a space velocity ofsubstantially from 0.50 to 4.0

feet per second, the crushed solids to be fluidized,

imparting to the mass thereof a turbulent motion simulating a boilingliquid, and like a liquid it will assume a fluid level in the layer 25.Feed solids are supplied until the layer reaches a fluid level 26 whoseelevation is controlled by the upper end of the spillpipe or transferconduit 4! and starts to drop or fall down that pipe, whereupon theconed valve 70 is opened to allow the spilling solids to fall onto theconstruction plate 44. This operation is continued until the level ofthe solids in the main or middle layer 42 is sufficient to seal thelower end of the pipe 4|. When the layer 42 has been about half formed,or formed to about half its normal height, the feed is stopped. Thetemperature of the solids in the layer 42 is made to rise by heat fromthe burners. When the layer reaches an operating temperature, feeding isstarted again and cone valve 13 at the bottom of spill-pipe 46 isopened. Solids from layer 42 spill over into spillor dippipe 46, whichdelivers them onto the partition 53 whereupon a layer 50 builds up to anelevation or liquid level 5! whereupon solids flow down discharge pipe54. The hot, treated solids submergedly delivered to the layer 50 arecooled in that layer by heat exchange with the current of air uprisingtherethrough to maintain combustion in the dissociation layer 42.Finished product is delivered through discharge pipe 54, the flow beingregulated by valve 55.

The foregoing describes, by way of illustration, a reactor furnaceof thetype with which this invention is to be associated, and in which itfinds its environment. Howeyer, the invention may be used with a singlebed fiactokfurnace as well as with a multi-bed furnace. TheTnvention isillustrated in Figure 2 which is a partition, such as ll, 44 and 53, butfor identifying purposes it will be given the reference numeral i I1,and an aperture l8 of any of those partitions, whose inner peripherywill be referred to as the bore H9. The reducer means H9 is indicated ascomprising a sleeve portion I20 having an inwardl extending annularflange 52!, defining a gas-flow passage or orifice I22. The flange 12!forms a shoulder portion with the sleeve portion 120, and the flange iZlshould be as thin as feasible for the thinner the better. However, itmust be strong enough to resist all working forces plus, say 2100 F. So,ordinarily a thickness of A; inch or more will be satisfactory. I23indicates screw, bolt, or other means for securing the reducer means H9in place in its aperture is so that it cannot inadvertently be displacedtherefrom. It is preferable to have the annular flange l2! as close tothe emission or outlet end of the aperture is (as shown in Fig. 3), butit is diflicult to secure it in such position, so the position shown inFig. 2 seems to be the more feasible. The gas-flow passage or orificeI22 is of a critical diameter that lies in a range of from substantiallyone-fifth to one-half the diameter of the bore 5 it so this permitslarger sized bores or apertures to be used than would otherwise be thecase, while still effecting the necessary velocity of uprisingfluidizing gas to and into the bed of solids thereabove. However, therelation of these parts should also critically be such that the velocityof the gas uprising in that portion of the bore l I 8 that is below thereducer H9 (or on the up-stream side thereof so far as the uprising gasis concerned) should be less than 30 feet per second and liein arange offrom substantially 20 feet per second down to substantially 15 feet persecond, if clogging dea partial view of.

posits on the bore of the aperture are to be minimized by assuring flowof gas therethrough more or less in filaments I24. The reason is that ifhigher velocities are realized, the gas ceases to flow in smoothfilaments through the reducer and instead, form turbulent eddies whichin turn produce, or tend to produce the undesired clogging deposits. Thedeposits are of solids, and especiall calcareous solids picked up orentrained as dust by the gas in its passage to the aperture. Thediameter of the orifice I22 should be small enough so that the pressureloss of gas uprising through it, expressed in equivalent inches ofwater, slightly exceeds the minimum pressure required for fluidization.This -minimum pressure is a function of the aperture spacing on thediaphragm or partition and the bulk density of the material beingfluidized. The diameter of the bore may lie between 2 to 5 inches,whereupon the diameter of the orifice lies between inch to 1 inchrespectively.

I claim:

1. In a gas permeable horizontally extending support of substantialthickness having tubular passageways therein for supporting a bed ofsolids in a reactor furnace, the improvement which comprises a gaspassage in said support and a thin plate having an orifice of areasubstantially less than the area of the gas passage fixedly mounted insaid gas passage so as to prevent deposition on the orifice.

2. A claim according to claim 1, wherein the area of the orifice is fromto of the area of the gas passage with which it is associated.

3. An apparatus according to claim 1, wherein the orifice is a sleevemember with an inwardly extending annular flange fixedly mounted in thegas passage.

4. An apparatus according to claim 1, wherein the horizontally extendingsupport is metallic and the orifice is an apertured plate weldedthereon.

5. Apparatus according to claim 1, wherein the horizontally extendingpartition comprises an arch of refractory material and the aperturestherethrough are greater in length than in diameter, and wherein thethin plate having an orifice is located within such apertures in theupper section thereof.

FRANK S. WHITE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number

